The present invention relates to a method and apparatus for inspecting the surface on an article, such as an airfoil.
An apparatus for inspecting the surface of an airfoil is disclosed in U.S. Pat. No. 4,125,317. The apparatus includes a laser which directs light to a lens. The lens focuses the light on the surface of the airfoil. The airfoil is rotated to cause the light to be sequentially focused at each point in a series of points on the surface of the airfoil.
The light is reflected from the surface of the airfoil to a linear array of photodiodes. The location at which the reflected light is focused on the linear array of photodiodes indicates the location of a point on the surface of the airfoil. Since the airfoil must be rotated and has a significant mass, the time required to rotate and accurately position the airfoil with each increment of rotation limits the speed with which the curvature of the airfoil can be determined.